The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
Wireless communication requires the use of an antenna to transmit and receive electromagnetic signals. Several antenna types are available for a variety of purposes and the choice of selecting one type of antenna or another typically depends upon the particular application of the antenna. To select an antenna, various operating characteristics of the antennas may be evaluated and compared to determine the type of antenna that provides the most benefit or is best suited for a specific application.
Occasionally, one antenna having all or most of the desired operating characteristics for a particular application may not exist and there may be several antennas having varying combinations of favorable and unfavorable aspects. For instance, a small antenna with a low profile and a wide bandwidth may generally be preferred for modern wireless communication. A microstrip or patch antenna is a relatively inexpensive antenna that is capable of being easily integrated with many electronic devices. Although the patch antenna may feature a low-profile, its relatively large size (approximately one-half wavelength) and narrow bandwidth (approximately 5%) may be a disincentive for its use in some wireless applications. However, various techniques have been developed to significantly reduce the size of the patch antenna. For example, by shorting one edge of the patch antenna and/or folding the patch antenna over itself, a reduction to one-fourth its original size may be achieved. Unfortunately, reducing the size of the patch antenna in this manner may also significantly reduce its bandwidth, e.g., 1.3% fractional bandwidth. The bandwidth of current patch antennas is therefore too narrow for practical use in short to medium range wireless communication systems, e.g., wireless microphones, wireless audio monitoring systems, local wireless data networks, wireless medical devices.